The present invention relates to apparatus for manipulating sheets, such as signatures, in bookbinding and other types of machines. More particularly, the invention relates to improvements in apparatus for converting a stream of partially overlapping single sheets, folded-over sheets or stacks of sheets into a row wherein the sheets overlap or substantially overlap each other. Such apparatus are normally used for stacking of newspapers or signatures.
The copending application Ser. No. 751,738 (some matter of which is disclosed in commonly owned Swiss Pat. No. 574,861) describes and shows an apparatus wherein a set of belt conveyors advances the stream of partly overlapping sheets in a downward direction toward the upper reaches of horizontal chains whereon the sheets are converted into a growing row (horizontal stack) of overlapping sheets between distancing elements of the chain conveyors. Fully grown rows are thereupon lifted off the chain conveyors and transported to further processing stations. The application Ser. No. 751,738 further discloses a pusher which includes several fingers pivotable about an axis which extends transversely of the path of downward movement of successive sheets of the stream. The fingers serve to push successive rearmost sheets of the growing row forwardly to thus provide room for the oncoming sheets of the stream. When the fingers assume their front end positions (as considered in the direction of movement of the growing row), their lower portions extend forwardly beyond the path along which the sheets of the stream descend toward the chain conveyors.
The just described apparatus has been found to be eminently suited for conversion of a stream of partly overlapping sheets into a row of fully overlapping sheets, especially if the thickness, stiffness and smoothness of the sheets are constant or practically constant.